1. Field of the Invention
The present invention relates to a method for producing N-methylolacrylamide by reacting acrylamide with formaldehyde or paraformaldehyde.
N-methylolacrylamide is a crosslinkable monomer widely used in fiber treatments, photosensitive resins, adhesives, paints and the like.
2. Description of the Related Art
Various methods for producing N-methylolacrylamide by hydroxymethylation of acrylamide with formaldehyde are so far known. For example, there are proposed a method of reacting a 60 to 97% aqueous acrylamide solution with formaldehyde in an aqueous solvent using an alkali catalyst (U.S. Pat. No. 3,064,050), a method of reacting acrylamide with formaldehyde without a solvent using a tertiary amine (e.g. triethylamine, triethanolamine) as catalyst (U.S. Pat. No. 2,864,861), a method of reacting acrylamide with formaldehyde in water or an organic solvent or without a solvent using a basic anion exchange resin as catalyst (Japanese Patent Application Kokai No. 49-14418, No. 49-36615 and No. 49-127912), etc.
However, these conventional N-methylolacrylamide-manufacturing methods have many problems to be improved to use them in industry. That is, side reactions cannot sufficiently be inhibited, so that by-products are accumulated in the reaction solution to lower the yield of N-methylolacrylamide; troublesome purification processes are required to obtain high-purity N-methylolacrylamide from the reaction solution; the amount of the catalyst used is large; and the catalyst is relatively expensive.